New research offers hope on ash dieback

The UK’s ash trees may have been thrown a lifeline thanks to the breakthrough discovery of an ash tree showing strong tolerance to the devastating fungal disease, ash dieback.

A team of researchers led by the John Innes Centre (JIC) in Norfolk identified the ash tree, which has been nicknamed ‘Betty’, by screening leaf samples against a set of genetic markers.

Since it was first identified in the wild by JIC Researcher Anne Edwards in 2012, ash dieback has been spreading throughout UK trees and woodlands, with experts warning that it may wipe out 90% of the country’s 2.2 billion ash trees. However, infection rates vary greatly between woodlands, indicating that some trees have higher levels of tolerance to the disease than others.

The research team, known as the Nornex Consortium, developed three genetic markers, which enabled them to predict an individual tree’s level of susceptibility to ash dieback. They discovered one wood in Oxfordshire where 90% of the ash trees had one or more of the markers, indicating some degree of tolerance, with one tree in particular – Betty – showing strong tolerance. However, the researchers also note that the frequency of trees with tolerance to ash dieback throughout the UK is thought to be just 1-5%.

The findings, which have been published in the report co-funded by Defra and the Biotechnology and Biological Sciences Research Council (BBSRC), offer hope to the future of ash trees in the UK. The report authors raise the possibility that ash seedlings with the markers could be used to selectively breed tolerant strains of trees with which to replant the landscape.

Speaking on BBC Radio 4’s Today Programme on 22 April, UK Chief Plant Health Officer, Nicola Spence, said: “We have reason to be optimistic now that we have the tools to look for tolerant trees in the landscape. Before we were looking for trees that look healthy through the Living Ash Project.”

She added that an extra £20 million has been invested into tree health over the last few years but insisted that the figure represented “good value” as it is helping to protect “£6 billion worth of economic, social and environmental value in our crops and trees”.

The Tree Council has welcomed the news but urged landowners, local authorities, and others involved in managing ash trees to remain vigilant to the signs and symptoms of ash dieback and other tree pests and to plan for a future with a changing ash population.